Tropine is the tropane
core structure part (nitrogenous bicyclic nucleus) and tropic acid is the ester
part of atropine (a tropane alkaloid).
Atropine is hydrolysed to tropine and tropic
acid. Tropine also called tropanol (chemical designation: 8-Methyl-8-azabicyclo(3.2.1)octan-3-ol)
is an alcohol which forms esters. There are stereoisomers
endo- and exo- stereoisomers.

Tropeine is an ester of tropine, either a natural alkaloid derived from plants or
semi-synthetic. The best known members of tropeine natural alkaloids are Hyoscyamine,
Atropine, Scopolamine, Ecgonine, Cocaine.

Tropinone,
bicyclic aminoketone, is a useful synthetic precursor
in the preparation of many tropane ring compounds including
tropine and atropine.

nor- is a chemical acronym and prefix
to describe the lacking of methyl chains that are
part of a larger molecule. Nortropine is a tropine compound lacking methyl chain
at nitrogen
carbon.